The following is a tabulation of some prior art that presently appears relevant:
U.S. patentsPat. No.Issue DatePatentee103,739May 31, 1870Hanks223,315Jan. 6, 1880Brower449,673Apr. 7, 1891Francis471,679Mar. 29, 1892Spruce560,111May 12, 1896Salot828,853Aug. 14, 1906Ives850,084Apr. 9, 1907Crocker1,239,494Sep. 11, 1917Lange2,107,921Feb. 8, 1938Weed2,131,626Sep. 27, 1938Keith2,165,929Jul. 11, 1939Lentz5,582,542Dec. 10, 1996 Stein5,810,649Sep. 22, 1998Oar6,393,712May 28, 2002Jansson7,144,310Dec. 5, 2006Longbrake7,335,093Feb. 26, 2008 Harrelson7,553,216Jun. 30, 2009Hyde8,197,304Jun. 12, 2012Hummel
There are many types of honing or sharpening guides available to the consumer. Many of these jigs are designed for specific tool types, such as for honing hand held wood carving tools used in woodworking, finish or rough carpentry, printmaking, jewelry making, metal smith or silver smith work and related arts and crafts.
For example, there are honing guides the type of which clamp an edge-tool such that a combined edge-tool and clamping jig are both manually run across an abrading surface. U.S. Pat. No. 449,673 (1891) Francis, U.S. Pat. No. 560,111 (1896) Salot, U.S. Pat. No. 1,239,494 (1917) Lange, U.S. Pat. No. 5,582,542 (1996) Stein, U.S. Pat. No. 7,335,093 (2008) Harrelson, U.S. Pat. No. 7,553,216 (2009) Hyde, are of this type. These types of honing guide jigs are generally used for sharpening or honing of flat edge tools such as hand plane blades, chisels and the like. A number of problems with these types of honing guides result when an abrading surface is used as a support base for a jig. With this type of a jig, a tool edge is un able to access the entire surface area of an abrading medium with unrestricted random motion. Since a portion of an abrading surface is used as a support base for a jig, a larger than necessary honing stone is required to hone a tool. This limits a users choices as to sizes of honing stones that can be used with these types of jigs. Smaller honing stones that a user owns are not useable with these types of honing guides.
Since some areas of an abrading surface are not accessible to a tool edge, un even wear of a honing stone or abrading surface can result. And since an abrading surface is used as a support base, with long term use, such can cause un wanted wear to a jig.
An interesting design is that of U.S. Pat. No. 7,335,093 (2008) Harrelson, of which aim was to address the need for a sharpening holder that allows access to a relatively larger surface area of a honing stone, then the prior art allowed. This embodiment offers a honing guide which moves in a side to side motion over the lengthwise surface area of a honing stone, and is supported by several wheels which run on an abrading surface. This design however still requires a significant portion of the surface area of the stone to support the honing guide. Although a honing stone can be rotated 180° so that both lengthwise edges of the honing stone can have access to a tool edge, a problem still remains for edge tools honed at low bevel angles on narrow stones. For example—the lower the bevel angle of a tool edge, the greater the protrusion distance from the front of the jig is required. Thus, although the side to side motion, which does have merit with the idea of providing greater access to the surface area of larger stones compared to the then prior art—the problem of providing greater access to the honing stone is still not solved for tools requiring low bevel angles on relatively narrow honing stones. For some of the narrower honing stones, a tool edge will not be able to reach the edge of the honing stone, since the stone is acting as a support base for the jig. In other words, for low bevel angles, this solution will require relatively wide abrading surfaces to both support the honing guide and the edge tool, in order to meet the longer protrusion distances required for low bevel angles. Another problem that this embodiment brings about, is if the user tends to hone many tools at low bevel angles; depending on the width of the honing stone, only the areas near the edges of a honing stone will come into contact with a tool edge. This can create a convex situation at the lengthwise center areas of some honing stones, since the edges of relatively narrow stones are receiving more abrasive action then the center of the stone.
Jigs that are designed in such a way that only a tool edge comes into contact with an abrading surface, and a jig base rides on a flat smooth work surface which supports both stone and jig base, could have been a solution to this prior art problem. Although these types of jigs offer an entire surface area of an abrading surface to a tool edge, a problem the applicant has found with these types of honing guides, is that when a honing stone of a different thickness is swapped in, bevel and skew angles at a tool edge change due to an abrading height differential.
This problem was partially addressed by honing guides designed for tools in which only the cutting edge comes into contact with an abrading surface for example as in U.S. Pat. No. 850,084 (1907) Crocker. This type of jig has been used to sharpen tools known as Gravers or Buins used in the printmaking or jewelry arts. Base height adjustability was in the original design; however, the Crocker solution does not address the problem of raising the base height of the jig perpendicular or normal to the work surface by the exact amount of a height differential between two abrading surfaces independent of any bevel and skew angle a tool is set. Thus, when adjusting the correct bevel angle for one abrading surface, it is not possible to maintain that angle when switching to another abrading surface of a differing thickness. Re adjustment of skew and bevel angles is required each time a different abrading height is used. The original patent shows adjustable base legs that can be locked into place by a thumbwheel. However when raising or lowering the base legs, the legs are at an angle and are not perpendicular to a work surface. What results is that each time a different stone is swapped in, more material will be removed from the tool edge than necessary, because the bevel and skew angle settings are slightly different when the tool edge is at a slightly different elevation. This causes additional honing time as well as un necessary tool wear, and thus shorter tool life. For this very reason, many of the honing guides on the market today for wider tool shanks have been designed such that a base of the honing guide rides on the abrading surface due to the difficulty in creating a system for vertical base height adjustability independent of bevel and skew angle settings.
The applicant has found it difficult to hone short shafted, tiny hand carving gouges used in the wood cut print making arts, such as Japanese style hand carving gouges, to a consistent edge. Tiny western style gouges used in fine detail work are also a challenge to hone a tool edge to a uniform profile. These tools need to be held to an abrading surface at a constant bevel angle and rotated along the lengthwise axis of the tool shank, while simultaneously passed over an abrading surface in a completely random motion. Some of these tools are less than 1 mm in cut width and have shanks that are removable from a tool handle, and are less than two inches long when purchased new. The prior art is lacking in a universal manual honing solution that can be used on small planar abrasive surfaces, that can be applied to these tiny gouges, to larger gouges and to wide flat shanked cutting edges such as plane blades. This is because it is difficult to find a solution to clamp short tool shanks and present them to an abrading surface at a low bevel angle without a honing guide base bumping in to the edge of a honing stone. As these smaller tools become shorter with use, it is difficult to hone a uniform edge profile due to less shank length to either hold on to, or clamp into a honing guide. The shorter one can sharpen these expensive tools, tool life is extended.
One design for gouges, v-tools and chisels is U.S. Pat. No. 5,810,649 (1998) Oar. This design offers complete access to an abrading surface since the support base does not ride on an abrading surface. However, the design requires that a work surface which supports the jig base, be coplanar with the abrading surface at all times. This design does not allow for quick and easy adjustment of the jig base. Instead, one must have a support base of the same thickness of the honing stone or abrading surface. Unless one has the equipment such as a power planer to fabricate several work surfaces of differing thickness, or the manual skills to fashion several work surfaces of uniform thickness using hand planes, the jig base will be unable to maintain consistent bevel and skew angles without repeated re adjustment each time a new abrading surface is swapped in.
For gouges in which a fingernail type profile is desired, the inventor knows of no solutions available to the consumer today, which are capable of honing a repeatable fingernail profile on a gouge, using a planar (flat) and non motorized abrasive surface. Tools used for sharpening—honing this type of edge profile generally employ a wet grinding wheel system and associated fixturing attached to a wheel system—for example as in U.S. Pat. No. 6,393,712 (2002) Jansson. This configuration is part of a complete motorized system to sharpen multiple types of tools, such as chisels, gouges, hand and power plane blades and the like, utilizing a slow speed wet grinding system. Although wet grinding systems are capable of honing a wide variety of tools, such requires expensive motorized equipment and grinding wheels or abrasive discs. The user is thus limited to a narrow range of grinding wheels which operate on motorized equipment, and is unable to fully utilize the diverse and wide ranging types of honing stones and abrasive papers or films available to the consumer today. Many wood carvers or crafts people also do not have access to a work shop and prefer to work in the home, and would prefer manually non motorized equipment.